SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d848762e63a10a9dc121e6ac2ae10ab4579bbd17bb760b85f6af6646aa9e5be' 
  AND token = 'z3IEicjqmWX8FVjs63iwmyfwW309KKJn8BSVZk+GN+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}